Qualifications Involve Data Extrapolation, Evidence Levels

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide, according to the American Heart Association (AHA). And common sense suggests that lifestyle factors such as consuming a well-balanced, nutritious diet and engaging in appropriate physical activity can play a significant role in CVD prevention.

Finding that the evidence largely supports that common sense advice, the AAFP has given its qualified endorsement to an American College of Cardiology (ACC) and AHA guideline(circ.ahajournals.org) on reducing cardiovascular risk in adults through lifestyle management. The guideline was published online last November by the AHA journal Circulation.

Overview of Recommendations

Like the previous ACC/AHA guidance, this guideline was initiated in 2008 by the National Heart, Lung and Blood Institute (NHLBI), which sponsored a rigorous systematic review of evidence on the topic by an expert panel that convened and developed three critical questions, interpreted the evidence provided and crafted the initial guideline. Then, in June of last year, the NHLBI began collaboration with the ACC and AHA to work with other organizations to develop the guideline recommendations.

Story highlights

The AAFP has posted its qualified endorsement of the American College of Cardiology and American Heart Association guideline on lifestyle management to reduce cardiovascular risk in adults.

The first qualification addressed the fact that the diet and activity consensus recommendations were extrapolated from evidence supporting the recommendations only for patients with high blood pressure and hyperlipidemia to the whole population.

The second qualification concerned the recommendation for individual salt restriction below 2,300 mg, which the AAFP found to be based on low-level evidence.

The Lifestyle Work Group panel comprised 12 members plus four ex-officio members with expertise in blood pressure, cholesterol, obesity and lifestyle management. These participants brought backgrounds of primary care, nursing, pharmacology, nutrition, exercise, behavioral science and epidemiology and included scientific staff from the NHLBI and the NIH.

Recommendations were written based on evaluation of randomized trials, meta-analyses and observational studies that involved normal weight, overweight and obese adults with and without coronary heart disease/CVD or related risk factors. Evidence reviewed ranged from 1998 to 2009, with the exceptions of a "landmark" 1990 study on lipids, meta-analysis review on physical activity through May 2011 and sodium intake evidence through April 2012.

A peer review panel under the direction of the NHLBI that included six expert reviewers and representatives from federal agencies initially examined the guideline. A second panel composed of four experts nominated by the ACC and AHA also reviewed the document.

Out of the evidence review came 10 lifestyle recommendations (eight dietary and two on physical activity). A condensed version of the guideline's recommendations follows.

Adults who would benefit from lowering their LDL cholesterol and/or their blood pressure should consume a diet that emphasizes vegetables, fruits and whole grains; includes low-fat dairy products, poultry, fish, legumes, non-tropical vegetable oils and nuts; and limits intake of sweets, sugar-sweetened beverages and red meats.

Adults who would benefit from lowering their LDL cholesterol should reduce dietary calories from saturated and trans fats and should aim for a diet that includes only 5 percent to 6 percent of calories from saturated fat.

Adults who would benefit from lowering their blood pressure should reduce their sodium intake to consume no more than 2,400 mg of sodium per day. Further reduction of sodium to 1,500 mg/day is associated with an even greater reduction in blood pressure. Reducing intake of sodium by at least 1,000 mg/day will decrease blood pressure, even if the desired daily sodium intake is not achieved.

Adults should engage in aerobic physical activity to reduce LDL cholesterol and non-HDL cholesterol and to lower blood pressure. This should include three to four sessions per week lasting an average of 40 minutes per session and involving moderate- to vigorous-intensity physical activity.

Qualifications Explained

The AAFP's endorsement of the guideline came with two qualifications, the first of which addressed the fact that the diet and activity consensus recommendations were extrapolated from evidence supporting the recommendations only for patients with high blood pressure and hyperlipidemia to the whole population.

AAFP member Doug Campos-Outcalt, M.D., M.P.A., of Phoenix, explained that this was a point of concern because it contradicted the U.S. Preventive Services Task Force (USPSTF) final recommendation(annals.org) on behavioral counseling to promote a healthy diet and physical activity for CVD prevention in adults with cardiovascular risk factors. Released Aug. 25, the USPSTF recommendation concentrated only on patients at highest risk for CVD. Campos-Outcalt noted there is a low yield from providing this advice to lower-risk individuals and that the evidence to support extending these recommendations to lower-risk patients is not substantial.

The second qualification concerned the recommendation for individual salt restriction below 2,300 mg, which the AAFP found to be based on low-level evidence.

Campos-Outcalt said the issue is deciding how much salt restriction is beneficial. He cited an Institute of Medicine study(www.iom.edu) from May 2013 that questioned the need to reduce salt intake below 2,000 to 3,000 mg. The study examined evidence that suggested low sodium intake could actually increase health risks in individuals who have hypertension, diabetes, chronic kidney disease or congestive heart failure, as well as those who are 51 or older or African American.